When to Plant Perennials In Your Garden

What Are Perennial Plants?

Perennial plants are those that live for more than two years. They may be deciduous or semi-evergreen, produce flowers or be grown for their attractive foliage. Herbaceous perennials die back beneath ground level for the winter months, sprouting up again in spring.

Technically, some shrubs and trees are perennial plants, as they live for much longer than two years. However, the term is most often used to describe smaller plants without any woody growth. Check some out at Gardeners Dream.

Examples of perennial plants include:

• Geranium
• Hosta
• Lavender
• Phlox
• Black Eyed Susan
• Verbena
• Poppy
• Heuchera
• Lupin
• Iris

What Season Is Best to Plant Perennials?

Perennials can generally be planted at any time of year, as long as the ground isn’t frozen. However, for the best results and healthiest plant growth, it’s best to put them in the ground in spring or autumn.

Planting in Spring

Spring is ideal for planting tender or less hardy perennials because they’ll have time to settle and establish before the harsh winter temperatures kick in. This is also the best time of year for buying perennials, as nurseries and garden centres have a huge range of perennial plants to choose from.

Remember that perennials planted in spring need watering regularly, especially as the drier summer weather starts to appear.

Planting in Autumn

Hardy perennials are best planted in autumn, while the temperature is still mild and the ground is soft but not water-logged. Planting at this time of year allows time to let the plants establish a root system before the growing season. Wet autumn weather also reduces the need for additional watering as there is usually plenty of autumn rain to absorb. Mulch autumn-planted perennials well before frosty temperatures take hold to offer insulation and added protection for delicate roots.

Putting perennials in the ground can be done at the same time as planting bulbs for spring flowers, minimising the time and effort spent adding colour and interest to the garden.

When buying perennials in autumn, don’t be put off by their appearance. Remember that these plants are about to enter their dormant phase and, in the case of herbaceous perennials, die back for winter. You may even get a bargain as garden centres want to sell perennials that might not survive the winter in thin plastic nursery pots.

Planting in Summer

Most perennials find heat and scorching sun rays stressful when newly planted. For this reason, we’d advise against planting in summer. If you must, be sure to keep the soil moist without water-logging it and provide some shade during the hottest part of the day.

Avoid planting perennials on summer mornings as the afternoon sun will put added strain onto the young plants. Instead, plant in the evening when the air is a little cooler, and the plants can settle into their new spot before experiencing high temperatures.

What is the Latest Date for Planting Perennials?

Generally, aim to have all your perennials planted by the end of October. However, if the season is particularly mild, you may be able to stretch planting into November. The key is to ensure perennials are in the ground and established enough to withstand harsh winter temperatures, which means you want to have them planted by late autumn, a few weeks before the first frost is expected.

Choosing the Right Day

It may be tempting to make the most of hot, sunny weather and spend the time outdoors planting perennials in the garden. However, it’s better to wait until a cooler, dry day to plant herbaceous perennials. Not only are these conditions less likely to stress the plants, but planting them in cloudier weather means you can spend the hottest days relaxing guilt-free.

When to Plant Perennials in Containers?

Perennials are ideal for planting in containers. Unlike annuals, they don’t need to be replaced every year and are generally low-maintenance plants. They may cost more than annual flowers, but they last for a few years, so often work out cheaper in the long run.

Because pots are shallower and hold less soil than the garden, it’s best to fill them with perennials in spring. This gives the root ball time to spread and become established before being challenged by frosty temperatures. Plant perennials in pots in early spring to get a head start on flowering. Perennials tend to be hardier than annuals and can be planted up to a month earlier in the season, filling pots and containers with colour for longer and providing a valuable nectar source for early bees.

You may wish to overwinter a perennial’s container in a greenhouse or cold frame or add extra insulation around the container to help it survive the winter months. Even well-established plants need a little more cold-weather preparation when grown in pots.

When to Divide Perennials

Many perennials have a clump-forming growth habit, which makes them perfect for propagating by division. Ideally, this should be done every 3 years or so to help promote vigorous growth. If your plant blooms fewer flowers than last year or the clumps start to look a bit congested, it’s time to dig it up and divide the root ball. Again, the best times of year for dividing perennials are autumn and spring, before the growing season begins.

Use a garden fork to loosen the soil and lift out the plant’s root system, then carefully tease the clumps apart. Ensure you leave at least 2 growth buds on each divided section. You might need to use a garden spade to separate stronger fleshy roots.

The new sections should be planted straight away at the same depth, and ideally in the same conditions, as the original plant. Ensure there is enough space to let the roots spread, and water the plants thoroughly after the soil has been filled back in. When replanting the divided perennials, mix in some well-rotted manure to give the soil a nutrients boost.

Top Tips for Growing Perennials

Perennials are generally low-maintenance plants that don’t need much care and attention to flourish. However, there are a few tips that help keep perennials happy and healthy.

• Mulch the soil surface around perennials with well-rotted garden compost or bark to help retain moisture, suppress weeds, and provide insulation from the cold.
• Support tall perennials with stakes early in the season to help keep them growing upright.
• Deadhead spent blooms to encourage a second show of flowers.
• Water regularly during dry weather, keeping the soil moist but well-drained.
• Keep the surrounding area free of weeds, remembering to remove seed heads and the whole root system of perennial weeds.